Problem: Balance the following chemical equation: $ $ $\text{Mg} +$ $\text{HCl} \rightarrow$ $\text{MgCl}_2 +$ $\text{H}_2$
Answer: There are $2 \text{ Cl}$ on the right and only $1$ on the left, so multiply $\text{HCl}$ by ${2}$ $ \text{Mg} + {2}\text{HCl} \rightarrow \text{MgCl}_2 + \text{H}_2 $ Now all atoms are balanced; the balanced equation is: $ \text{Mg} + 2\text{HCl} \rightarrow \text{MgCl}_2 + \text{H}_2 $